1. Field of the Invention
The present invention relates to hybrid optical disc in which multiple recording layers responsive to laser lights of different wavelengths are arranged in a laminating direction.
2. Description of the Related Art
Currently, Read-only type DVDs (Digital Versatile Disc) that uses a red laser light having the wavelength of 650 nm are produced on a commercial basis and are widely spread. This type of DVDs contains what is called “regional information” which defines regions where reproduction of that DVD is permitted.
The regional information is provided for the use in making arrangements between the timing of the theatrical opening of a movie and the timing of the circulation of a DVD in which the relevant movie is recorded. In general, a movie will open in theaters worldwide on various dates differing by country or region. Therefore, there is the necessity of preventing the reproduction of the DVD in such countries or regions that the circulation of the DVD precedes the theatrical opening of the movie, and to this end, the regional information is used to manage the authority of the reproduction of the relevant DVD for each country or region.
Regional code is incorporated in a DVD player in advance, and a DVD can be reproduced by the DVD player only when the regional information contained in that DVD conforms to regional codes in the relevant DVD player.
Japanese Laid-Open Publication No. 2004-185724 discloses that a player is equipped with an attachable and detachable local data holding means, and thereby, where that player is moved from one region corresponding to a certain regional code to another region, the player is still capable of reproducing DVDs in which the other region after the move is designated by the regional information in the DVDs.
Among all the optical discs currently placed on the market, only the DVD can contain the regional information, whereas the existing CDs (Compact Discs) are out of the scope for setting the regional information inside. Therefore, in the case of incorporating two layers of a CD layer and a DVD layer into one disc, in order to set the regional information, only contents retained in the DVD layer should be taken into account.
Recently, standardization is taking place as for the next generation DVD to which a blue laser light having the wavelength of 405 nm is used, and in the course of the standardization, it is reported that the inclusion of the regional information in the next generation DVD is being considered. Also consideration is made that two recording layers, one compliant with the next generation DVD format (hereinafter called HDDVD layer) and the other compliant with the DVD format (hereinafter called DVD layer), are arranged in a laminating direction. In this case, the regional information is to be inserted in both the HDDVD layer and DVD layer. To cope with this arrangement, one has to take into account, when setting the regional information to each layer, not only the contents retained in each layer per se but also the relationship between the contents and difference in format applied to each layer. When regional information is set up easily only in consideration of the contents of each layer, abnormality may be caused during the reproduction of the disc.
Now, it is determined that only one regional code can be set in the players capable of playing the next generation DVDs as well as DVDs, which is a restriction imposed to the players for the purpose of ensuring the security of the contents in the discs. It is one of the notable features of the DVD standard that the assignment of more than one regional code to a player is basically prohibited. Because of this, as described above, in the case of incorporating the two layers into one disc, one has to set the regional information for each layer while bearing in mind that only one regional information is settable in a player.
In case where only one set of regional information is embedded in the player, if the regional information retained in one recording layer (first recording layer) fails to match that in the other recording layer (second recording layer), a problem arises that only the contents retained in the first recording layer of the two can be reproduced in a region specified by the regional information retained in the first recording layer.
Specifically, assuming that the regional information in the HDDVD layer specifies Regions A and B, while that in the DVD layer specifies Region A, since a regional code of a player in Region B fails to match a region specified by the regional information in the DVD layer, the contents recorded in the DVD layer can not be reproduced in Region B. This will be problematic when contents information of the two recording layers is related to each other like that, for example, the contents information recorded in the DVD layer supplements with contents information recorded in the HDDVD layer. The region information of each layer must be set up carefully and proper so that the user of each country who uses a player may not be exposed to such inconvenience.
However, in standardization of next generation DVD, a new regional assignment different from what is specified by the DVD standard may be set up uniquely. If this happens, it becomes quite difficult to set up the regional information of each layer without inconvenience. Even if the respective regional information defines regions similar to each other, between these areas, the area which does not overlap each other occurs.
Specifically, in case that Region A is defined with respect to one certain region according to the regional assignment of the DVD standard while Region C is defined with respect to a combination of Region A1 which is part of Region A and Region B which is different from Region A according to the regional assignment of the HDDVD standard, assuming that the regional information specifying Region A and Region C is set in the DVD layer and the HDDVD layer, respectively, contents information in both the DVD layer and the HDDVD layer can be reproduced in Region A1, however, in Region B, contents information of the HDDVD layer can be reproduced while contents information of the DVD layer cannot be. Also, in this case, in an area falling outside of Region A1 within Region A, contents information of the DVD layer can be reproduced while contents information of the HDDVD layer cannot be. The larger the difference in the regional assignment according to the standard stipulated for the next generation DVDs becomes in comparison with that for the DVDs, the more significant such a problem becomes.
As clarified above, as long as the regional assignment according to the DVD standard is different from that in the next generation standard, there is a problem arising that setting the regional information properly in the DVD and HDDVD layers without causing any inconvenience to the user becomes extremely difficult, while restriction imposed to the player that only one region code can be set in the player participate in generating this problem.